Hi! I am a homeowner finishing up a new home abandonded midway by the builder in Arizona. He previously installed a recirculating pump on a big water heater, but while the checkbook is out, it seemed the right time to look into doing it "right".

The layout: 5500 sf house, 5 bathrooms. The utility room has the front loading washer and is the center of a triangle between between Leg A) 30 feet to the kids' jack and jill tub/shower and 60 feet to another a guest shower Leg B) 60 feet to the master w/ big ol' whirlpool tub, dual head shower with body bar and Leg C) 75 feet to the kitchen and 130 feet to one upstairs guest shower. Who knows how the original builder's plumber ran all the lines in a loop? I'm just saying there is a lot of pipe in them thar walls!

My plumber is suggesting a Rinnai 9.4 GPM attached to a 10 gallon "feeder/storage" tank, on which the existing recirculating pump will be installed. I guess the idea is that the small tank will only turn on the tankless heater when it recirculates enough to drop the temperature? I have a 500 gallon propane tank with feeding this closet where the magic will happen.

I want to make sure I'm not burning through the propane or wasting water trying to get hot water to the kitchen sink, nor do I care to run out of hot water while sandblasting my cares away in the shower with that body bar. Two adults will use the master, and two little kids are there half-time.

Can anyone tell me some pros and cons of doing it this way? What approximately should the whole thing cost, the unused tank heater is already out, the pipes are there, the gas line is there, etc.

I get confused when you go online and you can get the water heater itself for $1,100 or so, and his bid is $3,000. I've been really happy with his work on all the other fixtures he has installed...

what YOU can buy the heater for has absolutely nothing to do with what he would charge to furnish and install it. If you want to buy it and warranty it, and just have him install it, that will be cheaper, and if it were I that would be the way I would prefer to do the job. It would make my life a lot easier.

$3000 isn't enough for a tankless install without the tank and tying in recirc.

Whats wrong with earning a good wage?

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Yeah true its probably closer to $2000 in material but he didn't say that the guy had to supply a 500 gal propane tank. Maybe there is gas really close by and it's in a wood framed house so the venting is just one 90* and the termination kit.

But yeah you're right $3000 is probably a little low even for a job in my head I'm imagining to go VERY smoothly. For the most basic job I'd probably charge atleast $3500.

Funny how a lot of guys who would do a Power vent 75 gallon tank for $2500 all of sudden want $5K for a tankless ...that cost less. Anyway, Here is what I would look into and my opinion on your house.

First, you don't really need a 10 gallon tank. A 5gal would work fine. I know, I have the same set up but only two return lines and the same sqft with probably longer runs.

Second, Look into this option: Bring back your 3 return lines in 1/2" or 3/4. Tie them inot a Metlund D'mand system (The S-02) at the water heater. If you tie the 2 - 1/2" lines inot a 3/4 x 1/2 x 1/2 tee adn the third into a 3/4 x 1/2 tee, the pump will force the piping to flow at capacity. (Which will be about 5gpm per zone. Use push buttons at each sink/bathroom in the home. When you push a button the system will operate and you will have a lag time to get hot water of about 10-20 seconds. (not bad)

What you WON"T have is the huge energy hit you are about to install with the tank! Your 10 gallon tank on a recirce will cost you about $50/month if it's on a times adn about $75-$100 if you have constant recirc. I'm not guessing, I've been playing with mine enough to know and guess what? I'm going to ruip my tank out and put in a Metlund sometime this summer!

Tankless adn recirc can work very well. Choosing a system that owrkd "On Demend" like the Metlund lets you get the nearly instant hot water you want while not taking a big hit on energy in the process.

Tankless adn recirc can work very well. Choosing a system that owrkd "On Demend" like the Metlund lets you get the nearly instant hot water you want while not taking a big hit on energy in the process.

Basically there is a flow switch and a aquastat. Turning on any fracet operates the flow switch which is in series with the aquastat which turns off the recirc loop when it reaches the temp you have set.

Last Rinnai I installed which was pretty straight forward, just had to move the gas and water lines 8 feet, and drill a hole in the concrete wall for the vent pipe it ran $3600.

Scott a 75 gallon power vent is a simpler install than a tankless. 75 gallon Power vent heater uses 80 K BTU if I recall, and a tankless is 199 K BTU, so gas pipe sizing and run is different and needs to be upgraded for the tankless. Venting on the power vent is PVC SCH 40 piping, Rinnai uses a concentric vent pipe costs a little bit more than PVC pipe and fittings. Also around here I can buy a 75 gallon power vent heater for a 1/3 of the cost of a tankless unit. So I would have to say the price difference is justified. Oh btw the most expensive install I ever done was $4600, It was an 8 hour day to install the unit, so I did lose some on my labor after all the material was priced out.

One person, who became MY customer after it happened, paid $2,000.00 for a tank type water heater replacement. There is no relationship between what the heater costs and what you pay to have it installed.

First, in new construction I submit that the instalation of a Tankless v/s tank is quite similar in actual "work" Not to mention that a tankless is a heck of a lot easier to carry into the house
second, 3K is a great price for my area for new construction. I'd take that every day and be perfectly fine. (Costs of living adn doing business veries accross the country you know.

"z" "Scott, where in this posting did you get the idea and comparison to a 75G power vented tank? And then where did the $5,000 come from? Pay attention." Answer: I run into that bunch regualry here. Kick their butt and make more money than them with happier customers.

"3 push buttons at at different sinks? Thats beyond the $ they wanted to spend being they were concerned about $3,000." Answer: The buttons are a couple dollars each, wireless and fast to install. Also, by running a reciec "on Demand" you avoid having to pay for the little tank, it's maintenance, its power usage and the heat loss through the pipe you will have every time the timer makes it run when you don't need it.

5GPM per zone on a S-02? You bet, do your homework. THe pump has a curve that will give you 26GPM @ 32' HD. Certainly with the returns as I suggested we would flow the capacity of the piping once you account for other system losses through the piping system. With a large home and lots of pipe, I highly doubt that flows would be anywhere enough to cause erosion ot the system. And it's about $1/year to run instead of $20-$30/month for an electric tank. Of course if there is a flow noise one can simply "balance it down" a bit with a valve at the pump. Nowhere did he sayh what the piping is. While copper at high flow rates may give you noise or errosion, did you happen to know that constant hi-temp recirc can make CPVC fail? I've now seen 3 jobs, (Thankflully done by others) two resturants and a big house, where fittings are failing and leaking and the only common is a recirc system that's always on.

I would say that these are quite sound priciples really.

As a final word from me on cost, I see a lot more overcharging for tankless than I see undercharging. Just because one can make a lot more money on one job does not make it a good business decision. As an example I know a company here who wants about $5500 for a basic tankless installation. They feel they deserve to charge that much. I am glad they do. They do one or two a year. I (an others) get between about $2800-$3600 depending on models required, work involves etc etc. sometimes we can get a little lower. Sometimes it's a little more but that covers about 85% of them. Those of us in that range do probably 50+/year or more. The installations take about 3.5 to 4.5 hours on a retrofit. 2 can be done in a day sometimes. I once did 6 new construction installs in about 5 total hours! (one per home in the same development, same placement and about 1.5 hours of that 5 was prefab work) Like SR demonstrated sometimes jobs are harder than you expect. That can happen at any time with any product or service...Right?

I'm not taking shots at anyone. I'm just saying, we all do things a little different based on our comfort levels, experiance with a product or service, our costs and needs.

Living in a generally hot climate means that your incoming water temperature is probably fairly high most of the year. SO, getting the full output of the tankless is more likely. Keep in mind that the gpm rating is for a specific temperature rise, and many people will never see that with their cold water, especially in the winter.

When sizing a unit, you always need to determine what your peak gpm useage is. If you have a large tub, or multihead shower, or expect to run the DW, and maybe the WM at the same time, or have multiple showers going, you can max out a unit very quickly. The end result is that the outlet temperature will drop. This may be fine, if it is still hot enough for the intended task, but that variable outlet temperature can be frustrating. The small tank will help modulate that a little, but 5 or 10-gallons isn't much, and equates to less than a minute on a tub fill, or typically a couple of minutes on a shower(s).

Depending on the length and path of the supply and return lines, it could take much more than 20-30 seconds to get hot to a fixture. My small townhouse is only 1100 sqft, and it takes nearly a minute to get full hot to the furthest fixture without recirc...on a much larger house, it could take a lot longer. You don't want to plan for more than 5'/second for the water, and it takes awhile for the lines to get warm, even after the water does start to move. Most of the pumps on recirc are quite small, and don't move much water (they also don't use much electricity to run, either). If the water lines are well placed and insulated, they don't lose all that much heat. I find it more convenient to put the recirc on a timer, and just not have to think about it and have hot when I need or want it. It also works better for guests, who may have no idea or forget.

I think there is a little misunderstanding...the plan for the tank was as a storage tank, not a self-contained WH. So, when it cooled off, you'd need something to trigger another pump or valve to run water from the tankless to heat it back up, or resort to making it a stand-alone heater, either electric or propane. This would complicate the install either way. Some tankless systems void the warranty unless you use a buffer tank with recirc, so keep that in mind.

Has anyone thought of a eternal water heater? it is a tankless?? with a 3 gallon stainless steel tank, works great can be recirculated. heater can be set to keep tank hot or just heat when needed. solves cold water sandwich problems